Radio cabinet or the like



April 23, 1940.

W. J. B. STOKES, 2D

RADIO CABINET OR THE LIKE Filed Dec. 30, 1937 lNVENTOR Wilma i5; ism 3; 2 144 ATTO N E? Patented Apr. 23, 1940 UNiTED STATES PATENT OFFlCE RADIO CABINET OR THE LIKE tion of New Jersey Application December 30, 1937, Serial No. 182,454

3 Claims.

This invention relates to cabinets, panels and similar constructions formed of hard rubber or other thermo-plastic compositions and particularly to cabinets for radio receiving sets and like apparatus containing elements which become heated during operation.

It has been proposed heretofore to form radio cabinets of hard rubber whereas the use of panels formed of hard rubber as insulating members and for supporting dials and control elements is well known. However, in constructing small high powered. radio receiving equipment of the type most popular today, a large number of vacuum tubes operating at high temperatures are crowded into a small space and the cabinet or housing fits closely about the apparatus.

The low heat conductivity of hard rubber, asphaltic compositions and of many similar plastic, mouldable compositions renders them unsuitable for use in forming cabinets and panels for such apparatus because the heat transmitted to the material from vacuum tubes located in close proximity thereto cannot escape readily. Local overheating therefore occurs and large differences in expansion of different parts of the cabinet or panel as well as softening of the ma terial at high temperatures produces warping and distortion of the material and sometimes results in cracking thereof. For this reason it is impractical if not actually impossible in many cases to employ thermo-plastic materials in forming cabinets and panels for radio receiving apparatus and other similar types of equipment. On the other hand hard rubber and many thermo-plastic compositions are cheaper than the heat hardening resins and. like materials commonly employed in forming radio cabinets. Moreover, thermo-plastic compositions in general are easier to mold and have higher impact strength than do many of the materials now employed and therefore are preferred for such purposes when otherwise suitable. It is also possible to obtain many characteristic and attractive color effects in the molding of hard rubber which can not be obtained in molding resinous materials.

In accordance with the present invention thermo-plastic compositions and particularly hard rubber are used in forming radio cabinets and means are used in combination therewith which prevent local overheating with the attendent warping, distortion and cracking of the materal even when the surfaces of the cabinet are located in close proximity to elements of the apparatus which attain relatively high temperatures.

The advantages of the present invention may be attained in any of various ways, but I prefer in general to provide the material of which the cabinet or panels are formed with means serving to remove or distribute heat transmitted thereto. In its preferred form the invention embodies material having high heat conductivity positioned between the thermo-plastic material of the cabinet and those elements by which heat is given off. A sheet of metal, such as aluminum or copper,

may be employed for this purpose and may be po- 1 sitioned directly in contact with the thermo-plastic material or may be spaced therefrom to provide a small air space between the heat conducting material and the thermo-plastic material. Generally it is preferred to provide the heat conducting member with a polished surface facing away from the thermo-plastic material whereby heat radiated toward the material is reflected away therefrom and only a relatively small portion of such heat is absorbed by the heat con.- ducting material. Moreover, such heat as is absorbed by the heat conducting material flows rapidly through the material of high heat conductivity and thus is conducted away from the source of heat toward portions of the material which are at lower temperatures. The flow of heat into and through the thermo-plastic material occurs only very slowly so that no part thereof attains a very high temperature and local overheating of the thermo-plastic material is prevented. In this way it is possible to form radio cabinets, panels and other elements of material which could not ordinarily be used for such purposes or in such relations.

One of the objects of the present invention is to provide a novel type of radio cabinet or the like formed of thermo-plastic material and capable of use in close proximity to elements maintained at relatively high temperatures.

Another object of the invention is to provide radio cabinets, panels and similar elements formed of thermo-plastic material, such as hard rubber, with means for preventing local overheating of parts thereof.

These and other objects and features of the present invention will appear from the following description thereof in which reference is made to the accompanying figure of the drawing.

The drawing is a view partly in perspective and partly in section of a radio cabinet embodying the present invention.

In that form of my invention shown in the drawing for the purpose of illustrating the same, a cabinet indicated generally at 2 is formed of hard rubber, asphaltic composition or other marelatively low heat conductivity.

terial of a thermo-plastic nature and possessing The cabinet preferably is molded in a single integral piece which may be open at the bottom and rest upon a base 4 by which vacuum tubes 6 and other elements of the radio receiving apparatus or like mechanism are supported.

The top 8 of the cabinet as well as the end 10 and front I2 thereof fit closely about the vacuum tubes 6 providing a small compact structure. The inner surface of each of the walls of the cabinet which lies close to an element of the mechanism which becomes heated during operation is provided with means such as a sheet of aluminum, copper or other metal of high heat conductivity for conducting heat away from those areas thereof adjacent the heated elements to portions thereof which are at lower temperatures. As shown the sheet of material i4 located between the vacuum tubes 6 and the top 8 of the cabinet is in direct contact with the material of which the cabinet is made throughout the entire surface thereof, being embedded in the material with only the lower surface exposed so that it does not increase the thickness of the top appreciably.

The sheets of material it and i8 located. between the vacuum tubes and the end it and front iii of the cabinet respectively are shown as mounted in an alternative manner to provide a narrow air space 126 between the heat conducting sheet and the walls of the cabinet whereby the thermo-plastic material is further protected from the transfer of heat thereto. In this construction the sheets 36 and It are supported by spaced studs 22 projecting inwardly from the inner surface of the end and front of the cabinet. The studs are formed with heads 2 embedded in the material of which the cabinet is molded and the heat conducting sheet i8 is provided with openings 26 therein loosely fitting the studs to allow for relative movement of the heat conducting member and thermo-plastic material resulting from differences in the expansion thereof. The sheet i8 is shown as corrugated to allow for expansion of the heat conducting mateterial and to provide a surface which is more extended and reflects heat therefrom with greater diffusion than does the sheet it.

When employed on vertical or inclined walls of the cabinet this construction has the further advantage of inducing a circulation of air between the sheets it and i8 and the sides of the cabinet which further serves to prevent localized overheating of the thermoplastic material.

The heat conducting sheets employed, whether in direct contact with the thermo plastic material as in the case of sheet l4 on the lower surface of the top of the cabinet, or spaced from the thermo-plastic material as in the case of sheets IE and I8, are each provided with an inner surface 28 which is highly polished to reflect heat radiated thereto from the vacuum tubes or other heated elements within the cabinet. In this Way the amount of heat absorbed by the heat conducting members is reduced and the temperature thereof as well as the temperature of the material of which the cabinet is formed is maintained relatively low.

While the present invention is directed particularly to constructions wherein the cabinet is formed as a single integral body of moulded material such as hard rubber the invention is equally applicable to constructions embodying a single panel or a number of separate parts formed of thermo-plastic material. Certain features of the invention are also applicable to other types and constructions or members designed for use adjacent heated elements. It should therefore be understood that the form and construction of the parts employed and the shape and arrangement of the heat conducting members by which said members are secured in position may be varied as desired for any particular application. In view thereof it should be understood that the forms of my invention shown in the drawing and herein described are intended to be illustrative thereof and are not intended to limit the scope of my invention.

The term thermo-plastic as used throughout the specification and in the claims is intended to refer to products such as hard rubber, asphaltic compositions and the like which may be softened by heating, as distinguished from those materials such as phenol or urea condensation products or phthalic anhydrous glycerol compositions which are generally classed as resins and which when once converted into a hardened state are not thereafter softened readily on heating thereof.

I claim:

1. In a radio cabinet having a casing formed of molded thermo-plastic material of low heat conductivity and housing elements of a radio receiving set including a vacuum tube which generates heat during operation and is located within the casing and closely adjacent a wall thereof, the combination including means for preventing local overheating of said well by said tube comprising an extended sheet of material having high heat conductivity positioned between said tube and said wall and serving to conduct heat from points adjacent said tube to points remote therefrom and to distribute heat from said tube over an extended area of said sheet.

2. In a radio cabinet having a casing formed of molded thermo-plastic material of low heat conductivity and housing the elements of a receiving set including a vacuum tube which generates heat during operation and is located within the casing and closely adjacent a wall thereof, the combination including means for preventing local overheating of said wall by said tube comprising an extended sheet of metal having high heat conductivity and means supporting said sheet in position between said tube and said wall and spaced from said wall to provide an air space therebetween, said sheet serving to conduct heat from points adjacent said tube to points remote therefrom and to distribute heat from said tube over an extended area of said sheet.

3. In a radio cabinet having a casing formed of molded thermo-plastic material of low heat conductivity housing the elements of a receiving set including a tube which generates heat during operation and is located within the casing and closely adjacent a wall thereof, the combination including means for preventing local overheating of said wall by said tube comprising an extended sheet of metal having high heat conductivity and presenting a polished surface on that side thereof facing said tube and means supporting said sheet in position between said tube and said wall and spaced from said wall to provide an air space therebetween, said sheet serving to reflect heat away from said wall and to conduct heat from points adjacent said tube to points remote therefrom and to distribute heat from said tube over an extended area of said sheet.

WM. J. B. STOKES, II. 

